Biological fluid filtration method and apparatus

ABSTRACT

A biological fluid processing or fluid filtration system is provided having novel open and closed loop processing systems wherein the gases transferred into and out of the system during processing pass through a porous medium in upstream and/or downstream gas inlet or outlet housings or vents in a manner which precludes the fluid being processed or filtered from ever contacting the housings or vents. Each housing or vent is separated from the fluid by a column of gas in its respective transfer line. The upstream gas inlet housing or vent is in communication with the unfiltered biological fluid, and the downstream gas inlet housing or vent is in communication with the filtered biological fluid.

[0001] This application is a divisional of pending application Ser. No.09/688,999, filed Oct. 16, 2000, which is a divisional of applicationSer. No. 09/272,203, filed Mar. 19, 1999, now U.S. Pat. No. 6,171,493,issued Jan. 9, 2001, which is hereby incorporated by reference in itsentirety. application Ser. No. 09/688,999 is copending as of the filingdate of the present application.

CROSS-REFERENCE TO RELATED APPLICATION

[0002] application Ser. No. 09/688,999 claims the benefit, Under 35U.S.C. •119 (e), of the provisional application filed on Mar. 20, 1998,under 35 U.S.C. •111(b), which was granted Serial No. 60/078,848, and ofthe provisional application filed on Apr. 29, 1998, under 35 U.S.C.•111(b), which was granted Serial No. 60/083,484. The provisionalapplications, Nos. 60/078,848 and 60/083,484 are hereby incorporated byreference.

BACKGROUND OF THE INVENTION

[0003] 1. Field of the Invention

[0004] The present invention relates to a method and apparatus forprocessing biological fluids into their therapeutically valuablecomponents. More particularly, the present invention relates to a methodand apparatus for processing donated blood into its therapeuticallyvaluable components. Most particularly, the present invention relates toan improved method and apparatus for processing donated blood into itstherapeutically valuable components which uses improved open-loop andclosed-loop systems to substantially increase the recovery of all theblood products from the donated blood.

[0005] 2. Discussion of the Related Art

[0006] Methods and apparatus for processing blood are well known in theprior art. U.S. Pat. No. 3,892,236 to Djerassi shows an apparatus forthe continuous withdrawal of blood from a human donor, forcedextracorporeal circulation of blood of the donor with separation ofgranulocytes, and return by gravity of the leukocyte-poor whole blood tothe donor.

[0007] U.S. Pat. No. 5,126,054 to Matkovich shows a venting means forventing gas from the transfer line of a liquid delivery systemcomprising a housing, a first, liquid-wettable, microporous membranecarried in said housing so as to be in communication with the transferline, and a second, non-liquid-wettable, gas permeable microporousmembrane superimposed on said microporous membrane to the outward sideof the housing. Gas in the delivery system is vented from the system solong as the first microporous membrane remains unwetted by the deliveryliquid.

[0008] U.S. Pat. No. 5,451,321 to Matkovich shows biological fluidprocessing assemblies having a gas inlet, and/or a gas outlet.

[0009] While these devices are generally satisfactory, some of themethods and apparatus of the prior art leave a large amount ofbiological fluid trapped in various elements of the fluid processingapparatus. While the aforementioned U.S. Pat. No. 5,451,321 to Matkovichprovides for liquid trapped in various elements of the blood processingsystem to be recovered either by causing a volume of gas behind theentrapped liquid to push the liquid through those elements and into thedesignated collection bag, or by pulling the entrapped liquid into thedesignated collection bag by a pressure differential (e.g. gravity head,pressure cuff, suction and the like), the system still has severaldrawbacks. One drawback is that they require one or more nonwettable,gas permeable, membranes. This requirement can lead to increased costsover wettable membranes.

[0010] Therefore, those skilled in the art continue to search for amethod and apparatus to provide for optimal recovery of the biologicalfluid from biological fluid processing systems, cost reduction and easeof use, and have developed novel open and closed loop systems andmethods associated therewith to achieve this goal.

SUMMARY OF THE INVENTION

[0011] The problems of the prior art are solved by the present inventionutilizing novel open and closed loop biological fluid processing systemswhich all share the concept that the gases transferred into, out of, orwithin the biological fluid processing system have the transfer linesarranged or configured in a manner which precludes the biological fluidfrom ever contacting the upstream and downstream gas inlet or outlethousings or vents, or bypassing the fluid filtration or leukocytedepletion device. Gases are transferred into and out of the biologicalfluid processing systems through a porous medium in the upstream anddownstream gas inlet housings or vents.

[0012] Each housing or vent is separated from, and in communication withthe biological fluid by a column of gas in the transfer lines. Theupstream gas inlet housing or vent is in communication with theunfiltered biological fluid and the downstream inlet or vent is incommunication with the filtered biological fluid.

[0013] In one embodiment of the present invention, a biological fluidfiltration apparatus is provided which includes a fluid filtration orleukocyte depletion device having an inlet and an outlet, a fluidcontainer upstream from and elevated above said fluid filtration orleukocyte depletion device and having an outlet, a first conduit influid communication with the outlet of said fluid container and theinlet of said fluid filtration or leukocyte depletion device, areceiving container downstream of said fluid filtration or leukocytedepletion device and having an inlet, a second conduit in fluidcommunication with the inlet of said receiving container and the outletof said fluid filtration or leukocyte depletion device, an upstream gasinlet having one of its•ends elevated above said fluid container, andhaving its•other end in fluid communication with said first conduit, anda downstream gas inlet having one of its' end elevated above said fluidcontainer, and having its' other end in fluid communication with said orleukocyte depletion or fluid filtration device.

[0014] In another embodiment of the present invention, there is provideda closed loop fluid filtration or leukocyte depletion device including afluid filtration or leukocyte depletion device having an inlet and anoutlet, a fluid container upstream from, and elevated above, said fluidfiltration or leukocyte depletion device and having an outlet, a firstconduit in communication with the outlet of said fluid container and theinlet of said fluid filtration or leukocyte depletion device, areceiving container downstream of said fluid filtration or leukocytedepletion device and having an inlet, a second conduit in fluidcommunication with the inlet of said receiving container and the outletof said fluid depletion device and a bypass line in fluid communicationwith said fluid container and said receiving container and having a loopportion elevated above said fluid container.

[0015] In yet another embodiment of the present invention the upstreamgas inlet is eliminated and the downstream gas inlet is connected to thereceiving container instead of the fluid filtration or leukocytedepletion device.

[0016] In another embodiment of the present invention, the downstreamgas inlet may be eliminated.

[0017] In still another modification of the present invention, theupstream gas inlet housing or vent and the downstream gas inlet housingor vent may be part of the same inlet device.

[0018] Thus, it is an object of the present invention to provide animproved method and apparatus for filtering biological fluids.

[0019] It is a further object of the present invention to provide anopen gas vent that prevents premature gas introduction into the fluidstream in a biological fluid processing system.

[0020] It is a further object of the present invention to provide anopen loop biological fluid processing system with transfer lines orconduits arranged or configured in a matter which precludes thebiological fluid from contacting the upstream and downstream gas inlethousings or vents, or bypassing the biological fluid depletion device.

[0021] Another object of the present invention is to offer a widerchoice of materials which may be used in the gas inlet housings or gasoutlet housings or vents of biological fluid filtration systems. Thepresent invention does not require wettable membranes. The choice ofmembranes for the present invention is not limited.

[0022] Another object of the present invention is to provide a system ofthe foregoing nature where gas is transferred into and out of thebiological fluid processor through porous medium in the upstream anddownstream gas vents.

[0023] A still further object of the present invention is to provide anopen loop system of the foregoing nature where each gas vent isseparated from, and in communication with the biological fluid by acolumn of gas in the transfer lines or conduits.

[0024] A still further object of the present invention is to provide anopen loop biological fluid filtration system of the foregoing naturewherein the upstream gas inlet housing or vent, and the downstream gasinlet housing or vent may be a portion of the same inlet device.

[0025] A still further object of the present invention is to provide aclosed loop biological fluid filtration system having a bypass linebypassing the biological fluid filtration device, the bypass line isarranged such that a column of gas separates the unfiltered biologicalfluid upstream of the filtration device from the filtered biologicalfluid downstream of the biological fluid filtration device.

[0026] A further object of the present invention is to provide an openloop biological fluid filtration system having an upstream gas inletelevated above the level of the biological fluid container and having asatellite bag connected to the biological receiving fluid container.

[0027] Further objects and advantages of the present invention will beapparent from the following description and appended claims, referencebeing made to the accompanying drawings forming a part of thespecification, wherein like reference characters designate correspondingparts in the several views.

BRIEF DESCRIPTION OF THE DRAWINGS

[0028]FIG. 1 is an elevational view of a prior art biological fluidfiltration system.

[0029]FIG. 2 is an elevational view of a construction embodying thepresent invention.

[0030]FIG. 3 is an elevational view showing a modification of theconstruction shown in FIG. 2.

[0031]FIG. 4 is an elevational view of a further modification of theconstruction shown in FIG. 2.

[0032]FIG. 5 is an elevational view showing a further modification ofthe construction shown in FIG. 2.

[0033]FIG. 6 is an elevational view of a closed loop constructionembodying the present invention.

[0034]FIG. 7 is an elevational view showing a modification of theconstruction shown in FIG. 6.

[0035]FIG. 8 is an elevational view of a further modification of theconstruction shown in FIG. 6.

[0036]FIG. 9 is an elevational view showing a further modification ofthe construction shown in FIG. 6.

[0037]FIG. 10 is an elevational view showing a further modification ofthe construction shown in FIG. 6.

[0038]FIG. 11 is an elevational view showing a further modification ofthe construction shown in FIG. 6.

[0039]FIG. 12 is an elevational view of a construction embodying thepresent invention utilizing a satellite bag.

DESCRIPTION OF THE PREFERRED EMBODIMENT

[0040] The aforementioned U.S. Pat. No. 5,451,321 to Matkovich shows abiological fluid processing assembly for filter biological processessuch as blood. An example of the Matkovich apparatus is illustrated inFIG. 1. The apparatus has a blood collection bag 30 connected by a firstconduit 31 to a leukocyte depletion device 32. The leukocyte depletiondevice 32 is connected by a second conduit 33 to a blood receiving bag34. A gas inlet 35 having a cover or cap 36, is provided in fluidcommunication with the first conduit 31 downstream of said collectionbag 30, and a gas outlet 37 is provided in second conduit 33 downstreamof the leukocyte depletion device 32.

[0041] In one embodiment of the prior art, a first clamp 38 is placed onfirst conduit 31 downstream of the blood collection bag 30 and upstreamof the gas inlet 35, and a second clamp 39 is placed on the secondconduit 33 downstream of the gas outlet 37. In a typical operation theblood collection bag 30 is sterile and is connected to the conduit 31 asillustrated. The gas inlet 35 is comprised of a housing 41 and a porousmedium barrier 42 in addition to cover or cap 36. Additional details ofthe barrier 42 may be obtained by reference to U.S. Pat. No. 5,451,321.

[0042] Prior to the start of blood processing, the inlet clamp 38, theoutlet clamp 39, and the gas inlet 35 are all closed. The bloodprocessing is initiated by opening the inlet clamp 38, and allowing theblood to drain from the blood collection bag 30. A column of blood flowsthrough the first conduit 31 into the leukocyte depletion device 32displacing any gas within the blood processing system. No blood entersthe gas inlet device 35 since the gas inlet is closed. The displaced gasis expelled from the system through the gas outlet 37 since the secondclamp 39 is closed. As substantially all the gas is expelled from thefirst conduit 31 and the portion of the second conduit 33 leading to thegas outlet 37, the porous medium is wetted by the blood, and the bloodflow seizes or stops at the liquiphobic bearer in the gas outlet 37.

[0043] Once the gas outlet 37 is wetted, the second or outlet clamp 39is opened, and filtered blood flows into the blood receiving bag 34. Thegas outlet 37 need not be closed prior to opening of the outlet clampsince the gas outlet is sealed by the wetted porous medium. Blood flowsfrom the collapsible blood container or bag 30 through the leukocytedepletion device 32 and into the blood receiving bag 34 untilequilibrium is reached within the system and blood ceases to flow. Atthis point, all of the blood has not been processed through theleukocyte depletion device 32. The first conduit 31, the filter device32, and the second conduit 33 are filled with blood.

[0044] Removing the cover or cap 36 from the gas inlet 35 allows gas toenter the processing system and drive the blood through the leukocytedepletion device 32. However, since the filter medium 32A within theleukocyte depletion device 32 is wetted, the flow of blood seizes whengas fills the upstream chamber of the filter. When the blood flowseizes, the second or outlet clamp 39 is closed.

[0045] It can be seen that, at this point, the downstream side of theleukocyte depletion device 32, and the entire second conduit 33 arefilled with blood. With ever increasing need for blood and bloodproducts, those skilled in the prior art have strived to increase therecovery of blood, and such a relatively large quantity of blood beingleft in the device of the prior art is no longer satisfactory.

[0046] In order to solve the recovery problems present in the prior artdevices, the open-loop construction shown in FIG. 2 has been developed.There is shown a biological fluid filtration system 44 having aleukocyte depletion device 45 with a filter medium 46, an inlet 47, andan outlet 48. The leukocyte depletion device may be such as thebiological fluid filter shown in provisional application Serial No.60/083,484, which has been incorporated herein by reference, or anyother suitable fluid filtration or leukocyte depletion device.

[0047] A blood container 49 is provided upstream from, and elevatedabove said leukocyte depletion device 45. Blood container 49 isconnected to, or in fluid communication with, said leukocyte depletiondevice 45 through first conduit 50.

[0048] There is also provided a blood receiving container 52 downstreamof said leukocyte depletion device 45. Leukocyte depletion device 45 isconnected to blood receiving container 52 through second conduit 54. Anupstream gas inlet 56 is provided in fluid communication with said firstconduit 50, and a downstream gas inlet 58 is provided in fluidcommunication with said leukocyte depletion device 45, downstream ofsaid filter medium 46.

[0049] An inlet clamp 60 and an outlet clamp 61 may be provided. Itshould be understood that one or more of inlet clamp 60 and/or outletclamp 61 may be provided, and be well within the scope of the presentinvention.

[0050] Upstream gas inlet 56 may take the form of a vent line 62 beingconnected to an upstream gas inlet housing 64. Vent line 62 may have aU-shaped portion 62A to prevent drawing of gas into biological fluidfiltration system 44 until substantially all of the biological fluid hasdrained from the biological fluid container 49. The other end of ventline 62 should be at a sufficient height such that it is alwayspositioned above the level of the fluid in the biological fluidcontainer 49.

[0051] Upstream gas inlet housing or vent 64 has an inlet 65 and anoutlet 66. Interposed between the inlet 65 and the outlet 66 in asealing relationship is at least one layer of a porous medium 67. Theporous medium may be such as a bacterial retention medium, a viralretention medium, or other suitable medium.

[0052] In a similar manner, the downstream gas inlet 58 may comprise asecond vent line 70 connected to a downstream gas inlet housing or vent71 having an inlet 72 and an outlet 73. A cap or other closure 74 may beused in connection with the opening and the closing of inlet 72.Interposed in the housing 71, between the inlet 72 and the outlet 73 isa second porous medium 76. The second porous medium 76 may also be suchas a bacterial retention medium, a viral retention medium, or othersuitable medium.

[0053] As illustrated, upstream gas inlet housing 64 and downstream gasinlet housing 71 may be provided in a single novel inlet device 80having a barrier or wall 81 which prevents fluid communication betweenthe upstream gas inlet porous medium 67 and the downstream gas inletporous medium 76. The upstream medium 67 and the downstream medium 76may then be formed of a single sheet.

[0054] The upstream gas inlet 56 and the downstream gas inlet 58 may beplaced in any practicable location as long as they are located such thatthe blood product being filtered never contacts the porous medium 67. Inthe preferred embodiment illustrated the porous medium 67 containedwithin the housing 64 is elevated above the blood container 49, butother locations are well within the scope of the present invention.

[0055] In the method of blood processing embodying the presentinvention, the inlet clamp 60 and the outlet clamp 61 are initiallyclosed. The cap or closure 74 covering the inlet 72 of downstream gasinlet device, housing, or housing portion 71 is also in place.

[0056] The blood processing is initiated by opening the inlet clamp 60and allowing the biological fluid to flow through the first conduit 50.As the fluid flows past the junction 50A, some of the fluid will flowinto the upstream gas inlet 56 through vent line 62. A column of liquidof a predetermined, desired, length (shown as dimension A in FIG. 2),between the junction 50A and the bottom of the loop portion of 62A,prevents gas entry into the system until substantially all of thebiological fluid has been drained from the biological fluid container49.

[0057] The upstream gas vent may be thought of as a manometer measuringthe pressure at the junction 50A. As the level of fluid within thebiological fluid container 49 decreases, the pressure at the junction50A decreases and, therefore, the height of the fluid in the vent line62 decreases. When substantially all of the biological fluid has drainedfrom the biological fluid container 49, the atmospheric pressure actingon the column of fluid within the vent line 62 will cause all of thefluid within the upstream gas inlet 56 to drain into the conduit 50. Theremaining fluid contained with the upstream gas inlet line 62 is drainedinto the conduit 50 because the upstream gas inlet is open toatmosphere. Thus, dimension A in FIG. 2 must be of sufficient distancesuch that the above described sequence of events occur. At this point,the leukocyte depletion device 45 downstream of the filter medium 46 andthe second conduit 54 between the leukocyte depletion device 45 and theblood receiving container 52, are all filled with filtered biologicalfluid.

[0058] The filtered biological fluid or blood downstream of the filtermedium 46 in the leukocyte depletion device 45 may now be recovered byopening the cap or closure 74 covering the inlet 72 of downstream gasinlet device, housing, or housing portion 71. In place of cap 74, aclamp (not shown) could be used on second vent 70.

[0059] After this step substantially all of the blood previouslyunrecovered by the prior art devices is in the blood receiving container52. Any gas in the receiving container 52 and/or second conduit 54downstream of the disconnecting point of the blood receiving container52 may be pushed back up into the second conduit 54 by gently squeezingthe blood receiving container 52, and then the outlet clamp 61 can beclosed.

[0060] As is now evident, the construction shown in FIG. 2 provides aneasy method of drainage of substantially all of the biological fluidfrom the receiving bag 52 through the leukocyte depletion device 45. Inaddition, the biological fluid filtration system 44 in its preferredembodiment utilizes only a single housing in the inlet device 80, and asingle layer of porous medium and substantially all of the filteredbiological fluid is recovered. The system has a lower number of parts,is easier to manufacture, and recovers more biological fluid at a lowerper unit biological fluid processing cost.

[0061] Alternate embodiments of the construction shown in FIG. 2 areillustrated in FIGS. 3-5, with like numerals designating correspondingparts in the several views. Their operation can easily be understood bythose skilled in the art in view of the foregoing description.

[0062] A modification of the present invention utilizing only theupstream gas inlet 56 and a satellite bag 83 is shown in FIG. 12.Satellite bag 83 is connected in fluid communication with bloodreceiving container 52 by satellite conduit 84. Satellite clamp 85 opensand closes satellite conduit 84. In this embodiment of the presentinvention, the satellite bag is used to vent the gas displaced from thereceiving container 52. The volume of the satellite bag 83 should besufficient to accept all of the gas displaced. After all the blood hasflowed into the receiving container 52, the container is gently squeezeduntil all of the gas is vented past the satellite clamp 85, at whichtime the satellite clamp 85 is closed.

[0063] Referring now to FIG. 6, there is shown a closed loop biologicalfluid filtration system 90. As in previous embodiments of the presentinvention, there is a leukocyte depletion device 45 having a filtermedium 46, an inlet 47, and an outlet 48. The filter medium 46 isinterposed in a sealing relationship between the inlet 47 and the outlet48. The system 90 also includes a blood container 49 connected by firstconduit 50 to the inlet 47 of leukocyte depletion device 45. Inlet clamp60 is provided as before.

[0064] Provided downstream of the leukocyte depletion device 45 is ablood receiving container 52. A second conduit 54 is connected betweenthe outlet 48 of the leukocyte depletion device 45 and the inlet of theblood receiving container 52. Used in place of the upstream gas inlet 56and a downstream gas inlet 58 is a by-pass line 91, which may be openedand closed by by-pass clamp 92. A first end of the by-pass line 91 isconnected in fluid communication with the blood container 49 proximatethe outlet thereof, and the other end of the by-pass line 91 isconnected in fluid communication with the blood receiving container 52proximate the inlet thereof. The loop portion 93 of the by-pass line 91is positioned such that when the blood container 49 is full of blood,the blood will not reach the loop portion 93 and thus, there can be noflow of blood through the by-pass line. One such position is illustratedin FIG. 6 with the loop portion 93 elevated above the blood container49.

[0065] In place of loop portion 93, a one way check valve or otherdevice may be used such that a column of gas will always separate theunfiltered biological fluid upstream of the filtration device from thefiltered biological fluid downstream of the leukocyte depletion device45. The positioning of the loop portion 93, and the bypass line 91 mayalso be varied to accomplish this.

[0066] The method of operating the the closed loop embodiment of theinvention differs in several respects from the method used with the openloop embodiment. As illustrated in FIG. 6, the additional by-pass clamp92 is needed because no gas inlet or gas outlet devices are provided, aswere necessary in the prior art. Prior to the start of blood processing,the inlet clamp 60 is closed and the bypass clamp 92 is open. The bloodprocessing is initiated by opening the inlet clamp 60 and allowing bloodto drain from the blood container 49 through first conduit 50 into theleukocyte depletion device 45 and therethrough to the blood receivingcontainer 52. The blood does not by-pass the leukocyte depletion device45 because of the loop portion 93 of the by-pass line 91 being elevatedto a sufficient height. The gas within the closed loop biological fluidfiltration system 90 is displaced by the blood flow into the bloodreceiving container 52. As the blood container 49 approaches its nearlyempty condition, the gas stored within the receiving container 52automatically flows through the by-pass line 91 into the blood container49 and allows substantially all of the blood to be processed through theleukocyte filtration device 45. It is important to note that the chamberof the leukocyte depletion device 45 downstream of the filter media 46at this point will be filled with blood, as will the second conduit 54between the leukocyte depletion device and the blood receiving container52. If there is any gas left in the receiving container 52 it may bedisplaced into the by-pass line 91 by closing the outlet clamp 61,gently squeezing the blood receiving container 52 and closing theby-pass clamp 92. In this embodiment of the invention comprising theclosed loop biological fluid filtration system, the chamber downstreamof the filter medium 46 in the leukocyte depletion device 45 is notdrained of blood, nor is second conduct 54. However, the inlet deviceand the outlet devices of the prior art are eliminated, and a simplifiedsystem is provided.

[0067] Additional modifications of the closed loop biological fluidfiltration system 90 are shown in FIGS. 7-11. Their operation can beunderstood by those skilled in the art from the foregoing description.

[0068] Therefore, by carefully studying the problems present in priorart biological filtration fluid systems, I have developed a novel methodand apparatus for biological fluid filtration.

[0069] In accordance with the provisions of the patent statutes, thepresent invention has been described in what is considered to representits preferred embodiment. However, it should be noted that the inventioncan be practiced otherwise than as specifically illustrated anddescribed without departing from its spirit or scope.

We claim:
 1. A biological fluid filter comprising: a) an inlet section,said inlet section comprising a top wall and a downstanding peripheralside wall, b) an outlet section complimentary in shape to and bonded tosaid inlet section to form a chamber communicating with atmosphere, saidoutlet section comprising a bottom wall and upstanding sidewall, and c)a filter element mechanically held in place between said inlet sectionand said outlet section to divide said chamber into at least an inletchamber and an outlet chamber.
 2. The filter defined in claim 1, whereinsaid inlet section further comprises: a) an inlet, b) a first passage influid communication with said inlet, and c) a first outlet in fluidcommunication with said first passage and said inlet chamber.
 3. Thefilter defined in claim 2, wherein said outlet section furthercomprises: a) a fourth passage in fluid communication with said outletchamber, b) a third passage in fluid communication with said fourthpassage, and c) an outlet in fluid communication with said thirdpassage.
 4. A biological fluid filter, comprising: an inlet forcommunication with a biological fluid container; an outlet forcommunication with a biological receiving container for filteredbiological fluid; a filter housing containing said inlet and saidoutlet; a biological filter element sealingly mounted between said inletand said outlet; and, a vent filter element embedded in said biologicalfilter element.
 5. The biological fluid filter of claim 4, wherein saidbiological filter element is made of a liquiphilic filter medium.
 6. Thebiological fluid filter of claim 4, wherein said embedded vent filterelement is made of a liquiphilic filter medium surrounded by a solid orliquiphobic barrier.
 7. A biological fluid filter, comprising: an inletcommunicating with an inlet chamber; an outlet communicating with anoutlet chamber; a filter housing containing said inlet and said outletand said inlet chamber and said outlet chamber; a biological filterelement mounted between said inlet and said outlet; a first liquiphilicgas vent embedded in said biological filter element and surrounded by asolid barrier; and, a second liquiphobic gas vent embedded in saidbiological filter element.
 8. A fluid filtration system including: a) afiltration device, said filtration device having a filter media dividingsaid filtration device into an up-stream side and a downstream side, b)a storage container for holding filtered fluid, c) a second conduitconnected between the downstream side of said filtration device and saidstorage container, and d) a second vent line in fluid communication withthe downstream side of said filtration device and selectively open toatmosphere.
 9. The fluid filtration system defined in claim 8, andfurther including; a) a downstream gas inlet in fluid communication withsaid second vent line.
 10. The fluid filtration system defined in claim9, wherein said downstream gas inlet includes; a) an inlet open toatmosphere, b) an outlet connected to said second vent line, and c) atleast one layer of a porous medium interposed between said inlet andsaid outlet.
 11. The fluid filtration system defined in claim 10,wherein said downstream gas inlet further includes; a) a cap for theselective opening and closing of said inlet.
 12. The fluid filtrationsystem defined in claim 11, wherein said at least one layer of a porousmedium is a bacterial retention medium.
 13. The fluid filtration systemdefined in claim 11, wherein said at least one layer of a porous mediumis a viral retention medium.
 14. A fluid filtration system including: a)a fluid container, b) a first conduit in fluid communication with saidfluid container, c) a vent line in fluid communication with said firstconduit and having an outlet at a sufficient height so that a fluidbeing filtered does not exit, and having a portion which prevents gasentry into said fluid filtration system until a desired amount of fluidhas exited said fluid container.
 15. The fluid filtration system definedin claim 14, and further including: a) an upstream gas inlet housing influid communication with said vent line.
 16. The fluid filtration systemdefined in claim 15, wherein said gas inlet housing includes: a) aninlet open to atmosphere, b) an outlet connected to said vent line, andc) at least one layer of a porous medium interposed between said inletand said outlet.
 17. The fluid filtration system defined in claim 16,wherein said at least one layer of a porous medium is a bacterialretention medium.
 18. The fluid filtration system defined in claim 16,wherein said at least one layer of a porous medium is a viral retentionmedium.
 19. A fluid filtration system including: a) a filtration device,said filtration device having a filter media dividing said filtrationdevice into an up-stream side and a downstream side, b) a storagecontainer for holding filtered fluid, c) a second conduit connectedbetween the downstream side of said filtration device and said storagecontainer, and d) a second vent line in fluid communication with thedownstream side of said filtration device and selectively open toatmosphere.
 20. The fluid filtration system defined in claim 19, andfurther including: a) a fluid container, b) a first conduit in fluidcommunication with said fluid container, c) a vent line in fluidcommunication with said first conduit and having an outlet at asufficient height so that a fluid being filtered does not exit, andhaving a portion which prevents gas entry into said fluid filtrationsystem until a desired amount of fluid has exited said fluid container.21. The fluid filtration system defined in claim 20, and furtherincluding: a) an upstream gas inlet housing in fluid communication withsaid vent line, b) a downstream gas inlet housing in fluid communicationwith said second vent line, said upstream gas inlet housing and saiddownstream gas inlet housing contained in a single inlet device.
 22. Abiological fluid filter comprising: (a) an inlet section, (b) an outletsection complimentary in shape to, and sealingly connected to said inletsection, and (c) a filter element held in place between said inletsection and said outlet section to form at least an inlet chamber and anoutlet chamber, said filter element comprising a filter medium dividedinto two or more sections, separated from each other, so that thewicking properties of the filter medium used will not cause anysubstantial air entrapment in said biological fluid filter.
 23. A fluidfilter comprising: (a) an inlet section, (b) an outlet sectioncomplimentary in shape to, and sealingly connected to said inletsection, and (c) a filter element held in place between said inletsection and said outlet section to form at least an inlet chamber and anoutlet chamber, said filter element comprising a filter medium dividedinto two or more sections, separated from each other, so that thewicking properties of the filter medium used will not cause anysubstantial air entrapment in said fluid filter.
 24. A filter elementcomprised of a filter medium said filter medium divided into two or moresections, separated from each other, so that the wicking properties ofthe filter medium uysed will not cause any substantial air entrapmentwhen used in a biological fluid filter device.
 25. A fluid filtercomprising: (a) a filter housing, said filter housing having at leastone inlet and at least ne outlet, and (b) a filter medium separatingsaid filter housing into at least one inlet chamber and at least oneoutlet chamber, said filter medium comprising at least two sectionsseparated from each other such that substantially no air entrapmentoccurs within the filter housing.